Three-dimensional numerical simulations of the evolution of a contrail and its transition into a contrail-cirrus
1European Centre for Research and Advanced Training in Scientific Computation, URA CNRS/CERFACS no 1875, Toulouse, France
2Météo France, Toulouse, France
*now at: Department of Geography, King's College London, London, UK
Abstract. This study describes high-resolution numerical simulations of the evolution of an aircraft contrail and its transition into a contrail-cirrus. The contrail is modeled as a vortex pair descending in a stratified atmosphere where turbulent fluctuations are sustained in the late regime of diffusion. The focus of this study is laid on the three-dimensional vortex dynamics – including vortex instability and turbulence – and on the interaction between dynamics and microphysics and its role in determining the growth and the distribution of ice crystals. The results show the feasibility of three-dimensional simulations of the entire lifetime of a contrail until its transformation into a contrail-cirrus in supersaturated conditions. In particular, it is shown that the contrail-cirrus optical depth is maintained as the cloud expands, in agreement with available observations.